Radio receiving system



Nov. 24, 1925. 1,562,820

J. B. BRADY RADIO RECEIVING SYSTEM Filed A112. '22, 1923 lngtoz Patented Nov. 24, 1925.

UNITED "STATES- PATENTfOFFlCE.

JOHN B. BRADY, 0F SOMERSET, MARYLAND, ASSIG NOR T0 MORKRUM'COMPANY Ol! CHICAGO, ILLINOIS, A CORPQRATION 0F MAINE. I

ninro nncnrvrn'e srsrn'm.

To all whom it may concern: a

Be it known that I, JOHN B. BRADY, a citi; zen of the United States, residing at Somerset, county of Montgomery, and State of Maryland, have invented a certain new andv including an automatic receiving printer unit which may be set up quickly and placed and maintained in operation by one unskilled in the art for receiving news in print sent out from a central radio station.

Another object of the invention is to provide a terminal printer receiving apparatus with associated electron tube circuits with all circuits arranged to be supplied with power from the same source of power at the receiving station which is available for; lighting or other uses whereby installation of the apparatus for picking up news is reduced to merely lugging in a connection with a lighting socl et.

A further object of the invention is to provide an automatic printing apparatus for a radio receiving station wherein direct current is furnished to the local control circuit of the printer by rectifying an alternating current and reducing the electrical time constant of the local circuit to a minimum.

Another object of the invention is to pro-.

vide a single control at an automatic radio printer receiving station which may be op-' erated to simultaneously energize the filament and plate circuits of the electron tubes of the receiving apparatus and the relay, and

connect the local printer and its driving motor in circuit whereby the mere throwing of a single switch at the terminal receiving stae. tion is all that is necessary to place the automatic printer apparatus and associated receiving circuits in operation for takin' copy transmitted from a distant radio station. 7

Other and further objects of my invention will be understood from the specification hereinafter following and by reference to the accompanying wiring diagram showing the Application filed August 22, 1923. Serial No. 658,816.

circuit arrangement of the automatic printer I equipment at the receiver. A

ll y lnvention has been illustrated in combination. with automatic printer apparatus known as Teletype which is the invention of Charles L'. and Howard L. .Krum of Chicago, Illinois. This equipment is manufacturedby the Morkrum Company of Chicago and has proven highly successful in both short distance and transcontinental radio operation. While this particular printer equipment has been shown it will be understood that other types of automatic printers may be used and that no limitations upon the invention are intended. Heretofore automatic printer equipment in radio operation has required a considerable arrangement of wiring and has occupied a substantial amount of space. The large number of'circuits required to be supplied with energy has necessitated bulky storage batteries and inherent charging facilities which is very inconvenient in the type of installation in which an automatic printer receiver is most needed. My invention contemplates a compact automatic printer installation for picking up pressnews or other types of service broadcast from a central station to a number of outlying points. The apparatus is arranged in compact order to enable simple installation in business houses, banks, between warehouses and large stores and in all instances where wire facilities are inadequate or impracticable to obtain. The fre uency used for transmission may be very hlgh with an order of wave length as low as ten meters 1 in which instance signals may be conveniently concentrated in a particulardirection and certainprinters operated to the exclusion of others. By operation of the low wave lengths many channels of communication are available without interference. The signals at these wave lengths are quite sharp and very little static is encountered. 'The radio frequency energy collecting system at each receiver is set on, that particular frequency employed in operation: I have represented a coil antenna l'tuned by condenser 2 but it will be understood that any form of collector may be used.- The employment of a loop enables the apparatus as awhole to be installed in a busmess house without the necessity of running any conductors which may be undesirable for various reasons at the installation point. The radio receiving Lowell Patent 1,455,141 issued May 15, 1923.

. each character.

The alternating current hum in this receiver, while it is eliminated, is of small importance for a selective tone frequency circuit is employed for responding to the impulses which operate the automatic printer. The receiver illustrated includes three stages of radio frequency amplification obtained by means of tubes 3, 4 and 5. 'A detector 6 is employed coupled with a local oscillator 7. two stage audio frequency amplifier comprisingelectron tubes 8 and 9 functions to increase the amplitude of the beat note resulting from the combination of the frequency of the incoming printer impulses and the 10- cally produced oscillations derived from generator 7. The transformer 10 is provided with a primary winding 11 supplied from the alternating current lighting source at the receiving station indicated by conductors 12. A plurality of secondary windings 14, 15, 16, 17 and 18 function to supply en orgy to the several branch circuits of the apparatus. Winding 14 supplies the filament lighting circuit for the various electron tubes in the set. Winding 15 supplies the plate energy for the electron tubes which is rectified by two electrode tubes19 having its filament heated by energy delivered by winding 16. Other rectifier tubes 20 and 21 are shown having their cathodes energized from winding 18 while winding 17 supplies energy which is rectified by tube 20.

The signals used in the automatic printer system comprise successions" or groups of modified impulses extending through a definite number of successive time intervals for The characteristics of the signaling impulses will be more clearly understood by reference to John B. Bradys Patents 1,485,212, dated February 26, 1924, and

1,523,377, dated January 13, 1925. An electron tube relaycircuit 22 comprising tubes,-

23 and 24 and selectively tuned input circuit 25 is providedand set for the particular audio note employed in the system. A sharply responsive mechanical relay 26 is employed in the output circuit of the electron tube relay 22. A negative bias is applied to the grid circuit of tubes 23'and 24 y means of energy delivered by rectifier tube 2Q contrellable to a .fine degree by regulation of the cathode temperature of tube'20.

The mechanical relay 26 has armature and cooperating contacts'27 connected in the 10- cal printer circuit with Teletype magnet coils 28 through terminal board 29 beneath the base of the Teletype printer unit 30. Direct current is supplied to the local consource as set forth in Dunmore and.

trol circuitfrom rectifier tube 21 having its plate circuit energized. from the lighting circuit leads 12 through conductors 36. An

auto; transformer 32 fixes the value" of the dlrect current in the local control circuit and resistance31 serves to reduce the electrical inertia or thetime .constant of the local circuit to a minimum to insure the sharp response of the circuit to the received radio impulses. The driving motor 33 on the Teletype printer base 30 is supplied with energy through leads 37. The motor when operating on alternating current has been found to produce undesirable roars, noises .and interference in the electron tube circuits of the receiver and the electron tube relay,

unless carefully screened, and it is therefore desirable that the motor.33 be a direct current machine. Leads 37 are therefore taken to the auto transformer 32 tapped at 34 as indicated and direct current supplied by rectification of the alternating current source obtained from leads '12 through con-,

ductors 36 through tube 21. In lieu of the rectifier interposed in the motor circuit the leads 37 may be connected through dotted line conductors 35 direct with the lines 12 1 through connections 36 and the motor driv en from alternating current, other precautions being taken taken for the elimination of interference in the tube circuits.

A master switch 38 is provided which.

places the primary winding 11 on the power line 12 and simultaneously lights the filaments of the electron tubes 3, 4, 5, 8 and '9 of the receiver, tube 7 of the local oscillator and tubes 23 and 24 of the tuned relay circuit. The .plate energy is also supplied to all of these tubes simultaneously. The rectifier tubes 19, 20, and 21 have their filaments lighted simultaneously'andthe energy which is to be rectified supplied simultaneously to the plate circuits. While several rectifier tubes have been shown other'forms of rectifiers may be used and combined to supply the several circuits concurrently. In the local circuit for the Teletype magnet coils it is important that-a steady direct currentfrom rectifier 21 be supplied. The signalling impulses received by the loop col lector 1 and reproduced in the electron tube circuits follow in extremely rapid succes-' sion. The mechanical relay. armature 27 must follow these impulses and the local circuit including the rectifier unit and the Teleset forth in the John B. Brady patents above cluding the radio frequency energy collecting means, the power transformer 10, andthe automatic printer unit with merely a flexible cable lead represented by conductors 12 which may be provided with a suitable adapter to be plugged into the source of power at the receiving station. The com{ pactness of the apparatus enablesthe system to be conveniently assembled at the re ceivin point for the reception of signals direct 1n rint from a. distant transmitter.

While I ave described my invention in a certain limited embodiment it is to -be understood that modifications may be made and" that I intend no limitations upon the inven-,

tion other than are imposed by the scope/of the appended claims.

What I claim anddesire to secure by Letters Patent of the United States is as follows:

1. An automatic radio receiving apparatus comprising in combmatlon anelectrontube radio recelver arranged to respond to groups of impulses of energy extending through a definite number of successive time intervals for. each signal, means operated by said electronvtube rece ver for openmg and closing a local circuit in accordance with said impulses, automatic character selectingmeans connected in said local circuit, a source of alternating current and a rectifier connected between said source of alternatin current and said local circuit whereby said automatic character selecting means operates in accordance with said impulses with negligible electrical inertia.

tus comprising in combination an electron An automatic radio receiving .apparalocal circuit, a source of alternating cur rent and means interposed "between said source of alternating current and saidlocal circuit whereby said automatic character se-- lecting means operates in accordance with said'impulses withnegligible electrical lag for selecting a character simultaneously with i i the receipt of a particular succession of impulses.

3. An automatic radlo'recewmg'appara-f tube radio receiver arranged. 'to respond to impulses of energy extending through a defi nite number ,of successive time intervals and forming acha-racteristic'ally timed succession of impulses for each signal, an elec-' tron tube relay connected. therewith, a

mechanical relayactuated' thereby in accordance with said impulses, automatic character selecting and printing apparatus includ- 76 ing a-driving motor and an'electro-magnet, a local circuit containing the contacts of saidmechanical. relay and said electro-magnet, a source of alternating current, connections between said source and said apparatus for supplying power to said a 'paratus and .means connected'between said source and. said local circuit for energizin said local circuit with direct current w ereby said electro-magnetis caused to sharply respond tov said impulses for effecting the se-- lection of acharacter represented by a particular succession of impulses.

P JOHN B. BRADY. 

